Extended Spectrum -Lactamase-Producing Escherichia Coli in Clinical Isolates in Benghazi, Libya: Phenotypic Detection and Antimicrobial Susceptibility Pattern

-lactams are the most widely used group of antimicrobials; however, growing resistance to these invaluable drugs mediated by extended spectrum -lactamase (ESBL) enzymes is a major concern. The present study was undertaken to determine the prevalence of these enzymes and their effect on antimicrobial susceptibility pattern by different phenotypic detection tests in clinical isolates of Escherichia coli in Benghazi, Libya. Antimicrobial susceptibility testing was carried out by Kirby-Bauer method. Ceftazidime and cefotaxime were used for screening potential ESBL producers. Confirmation was done by a combination of double disk synergy test (DDST) and phenotypic confirmatory disk diffusion tests (PCDDTs).
A total of 120 E. coli strains (40 urine, 20 sputum, 20 blood, and 40 wound swabs) from inpatients at different hospitals of Benghazi, Libya, were included in the study, of which, 24 (20%) isolates were ESBL producers. The resistance pattern to the tested antibiotics was as follows: ampicillin (80% ), co-trimoxazole (60%), ciprofloxacine (40%), cefotaxime (30%), ceftazidime (30%), Ceftriaxone (30%), gentamicin (30%), cefpirome (35%), ofloxacin (30%), imipenem (25%), and nitrofurantoin (40%).
All the isolates tested showed resistance to two or more drugs and were considered to be multidrug resistant. A higher rate of ESBL production and multidrug resistance was seen among isolates from pus swabs as compared to other sources. ESBL producers mediated high resistance to both -lactams and non--lactams. Prolonged hospital stay and prior use of third-generation cephalosporins were identified as important risk factors for ESBL acquisition.
There is insufficient data regarding ESBL prevalence among E. coli strains from Benghazi, Libya. ESBLs not only pose a great threat to future of -lactams, but they also endanger the utility of many non--lactams. To ensure rationale in antibiotic treatment, ESBL detection and reporting assumes a priority in near future in Benghazi, Libya.